An atomizer employing surface acoustic waves is described in "Surface Acoustic Wave Atomizer with Pumping Effect" of Proceedings of 8.sup.th IEEE International Workshop on Micro Electrictro Mechanical Systems 30 Jan.-2 February 1995 Amsterdam, The Netherlands, in detail. FIG. 1 illustrates the atomizer which has been described in this literature. The atomizer comprises an oscillator 3 having a pair of interdigital electrodes 5 and 5 on its surface for generating surface acoustic waves, a cover 4 arranged on the oscillating surface side of the oscillator 3, and a tube 1. A liquid 2 to be atomized passes through the tube 1 as shown by arrow A, to be supplied into a clearance between the oscillator 3 and the cover 4. The liquid 2 flowing out from the clearance between the oscillator 3 and the cover 4 is atomized and sprayed by surface acoustic wave vibration.
In the atomizer shown in FIG. 1, various problems arise when the liquid supply quantity and the atomization quantity are unbalanced. If the liquid supply quantity is excessive, an overflow takes place and the atomization may stop. If the liquid supply quantity is insufficient, on the other hand, the atomization becomes so intermittent that continuous and smooth atomization cannot be attained. Further, high electric energy is required for atomizing and spraying the liquid with only vibration of surface acoustic waves, and it is difficult to perform a desired operation with driving by a battery of small power.